The client's in-flight flag covers the menus of one page only. A push reads YouTube, then writes both sides for seconds and commits step by step, so a row lock ends at its first commit: two tabs, or a push and the scheduled mirror refresh, could interleave into a doubled YouTube item or a baseline recorded over the other's writes. `sync_claim` takes a session-level advisory lock on a connection of its own (it survives those commits; a crashed worker's lock dies with its connection, so no claim column is left stuck). Push and revert answer 409 `sync_busy`; the scheduled refresh skips a list being synced and picks it up next run.
112 lines
3.8 KiB
Python
112 lines
3.8 KiB
Python
"""E28 review C1 — one YouTube sync of a playlist at a time, whoever starts it.
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A push reads YouTube and then writes both sides for seconds, committing step by step, so the
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client's in-flight flag (one page's menus) and a row lock (gone at the first commit) both leave two
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tabs, or a push and the scheduled mirror refresh, free to interleave. The claim is an advisory lock
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on a connection of its own; the test holds it from outside, the way a second request would.
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"""
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from sqlalchemy import text
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from app.auth import require_write_scope
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from app.models import Playlist
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from app.routes import playlists as plroutes
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from app.sync import playlists as plsync
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def _linked(db, user, *, source="local"):
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pl = Playlist(user_id=user.id, name="L", source=source, yt_playlist_id="PL123")
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db.add(pl)
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db.commit()
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return pl
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class FakeYT:
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"""YouTube as far as these routes read it: two playlists, none with items."""
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def __init__(self, *_):
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pass
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def __enter__(self):
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return self
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def __exit__(self, *_):
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return False
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def iter_my_playlists(self):
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return [{"id": "PL123", "title": "Renamed"}, {"id": "PL999", "title": "New"}]
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def iter_my_playlist_video_ids(self, _ytid):
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return []
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def iter_playlist_items_with_ids(self, _ytid):
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return []
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def get_playlist_snippet(self, _ytid):
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return {}
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def test_push_and_revert_refuse_while_the_list_is_claimed(
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db, as_user, make_user, override_dep, monkeypatch
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):
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user = make_user()
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pl = _linked(db, user)
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override_dep(require_write_scope, lambda: user)
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monkeypatch.setattr(plroutes, "has_read_scope", lambda u: True)
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ran: list[str] = []
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monkeypatch.setattr(plroutes, "YouTubeClient", FakeYT)
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monkeypatch.setattr(plroutes, "plan_merge", lambda d, u, p, live: {"units_estimate": 0})
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monkeypatch.setattr(plroutes, "merge_playlist", lambda d, u, p, live: ran.append("push") or {})
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monkeypatch.setattr(plroutes, "repull_playlist", lambda d, u, p: ran.append("revert") or {})
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c = as_user(user)
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with plsync.sync_claim(db, pl.id) as free:
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assert free
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for path in ("push", "revert-youtube"):
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r = c.post(f"/api/playlists/{pl.id}/{path}")
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assert r.status_code == 409
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assert r.json()["detail"] == {"code": "playlist", "reason": "sync_busy"}
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assert ran == []
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# Released on the way out: the same list syncs again, and a claim is per list.
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assert c.post(f"/api/playlists/{pl.id}/push").status_code == 200
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assert c.post(f"/api/playlists/{pl.id}/revert-youtube").status_code == 200
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assert ran == ["push", "revert"]
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def test_a_claim_is_released_when_its_block_raises(db, make_user):
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pl = _linked(db, make_user())
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try:
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with plsync.sync_claim(db, pl.id) as free:
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assert free
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raise RuntimeError("boom")
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except RuntimeError:
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pass
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# Asked of pg_locks, not by claiming again: a lock leaked on a pooled connection would be granted
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# again to that same connection (advisory locks are re-entrant per session).
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held = db.scalar(
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text("SELECT count(*) FROM pg_locks WHERE locktype = 'advisory' AND objid = :id"),
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{"id": pl.id},
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)
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assert held == 0
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def test_the_scheduled_refresh_skips_a_mirror_being_synced(db, make_user, monkeypatch):
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user = make_user()
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busy = _linked(db, user, source="youtube")
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replaced: list[int] = []
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monkeypatch.setattr(plsync, "has_read_scope", lambda u: True)
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monkeypatch.setattr(plsync, "YouTubeClient", FakeYT)
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monkeypatch.setattr(
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plsync, "_replace_items_from_youtube", lambda d, yt, p, ids: replaced.append(p.id)
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)
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with plsync.sync_claim(db, busy.id):
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out = plsync.sync_user_playlists(db, user)
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assert out == {"synced": 1}
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assert busy.id not in replaced and len(replaced) == 1
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db.refresh(busy)
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assert busy.name == "L"
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